Dispensing apparatuses for liquids in which the apparatus includes a container for the liquid and is provided with, or connected to, a flexible dispensing part are commonly used for dispensing such diverse liquids as for instance liquid soap, foam soap, alcogel, disinfecting or anti bacterial liquid, and lotion. The flexible dispensing part is filled with the relevant liquid and subjected to an external force in order to dispense the liquid therefrom. A user may apply a force on the flexible dispensing part directly or indirectly. The flexible dispensing part may be of such a size that a suitable or desired volume, e.g. 1 milliliter, of the liquid is dispensed upon complete actuation of the flexible dispensing part.
U.S. Pat. No. 3,741,439 discloses a viscous liquid dispenser suitable for dispensing contents of collapsible tubes. An elastic tubing portion is connected to the collapsible tube and affected by a dispensing mechanism including two levers, a dispensing lever and a movable lever, in order to dispense liquid from the elastic tubing portion. The dispensing lever has two arms, a lower arm and an upper arm, each one on a respective side of a fulcrum. The movable lever has its fulcrum at one end thereof. The upper arm of the dispensing lever bears against a shim on the movable lever such that, during a dispensing stroke of the dispensing lever, the upper arm moves along the shim towards the fulcrum of the movable lever. The lower arm of the dispensing lever is subjected to a force by a user to perform a dispensing stroke when viscous liquid is to be dispensed. During the dispensing stroke, the dispensing lever rotates about its fulcrum and the upper arm presses against the shim of the movable lever. Since the lower arm of the dispensing lever is longer than the upper arm, a force increasing leverage is achieved between the force applied by the user and a force by means of which the upper arm presses against the shim of the movable lever. However, during the dispensing stroke, the upper arm moves along the shim of the movable lever and a leverage of the movable lever decrease from a maximum value at the beginning of the dispensing stroke. Accordingly, a user must apply an increasing force as the dispensing stroke progresses to achieve the full dispensing stroke.
U.S. Pat. No. 6,540,110 discloses an apparatus for dispensing a free-flowing product in a bag. By means of a squeezing device a user may dispense a portion of the free-flowing product from an apportioning chamber of the bag. The squeezing device includes an abutment wall, against which the apportionment chamber abuts, and hand-actuated pressure-exerting parts, including a hand lever and a pressure-exerting pivoting part. The pressure-exerting pivot part clamps the bag in the region of the apportioning chamber and squeezes free flowing product therefrom upon a user actuating the hand lever. The leverage between the hand lever and the pressure-exerting pivot part appears to be substantially fixed over the dispensing stroke of the hand lever.
A complete actuation of a flexible dispensing part for dispensing liquid may be difficult to achieve. Some dispensing mechanisms require a user to apply an increasing force to achieve such complete actuation. Thus, it may be difficult to dispense a desired volume of liquid.